Need Different Rifle In Op Flashpoint Red River

Reached the mission called "The Wrong Way". Have got to defending the second line but I only have a rifle without telescopic sight and pistol. Result is that you cant see the PLA until it's too late and you get over run. All the walkthrus I've seen have the rifle with telescopic but I don't have that!

I've even tried going back to the start but they always give you these weapons when you start this mission.